Research proposed will include: (1) the identification of the growth inhibitory (towards formate-grown Pseudomonas oxalaticus) substance in the mixture of 2-carboxyhexitol-1,6-bisphosphate and the derived lactones, (2) a further characterization of the mode of action of the growth-inhibitory substance, (3) further characterization of the observed inactivaton of RuBP carboxylase/oxygenase from P. oxalaticus by Co ion generated in situ and by irreversible action-site reagents, (4) probing for the existence of monomeric catalytic species of this enzyme, and (5) further characterization of the activation and reaction mechanisms for RuBP oxygenase from P. oxalaticus.